Using Mezzmo v4.1.3.xx This is an annoyance and has confused me a few times but I think I have figured out what is going on. Here's the scenario:

Start the Mezzmo App fresh and select the Details View for the list of files. Note that none of the columns in the details view indicates any sorting of the view.
Click on a Playlist. The playlist will display in whatever order it was defined with.
Click on a detail view column to sort the list - pick some sort that is different from the sort defined in the playlist.
Now click on any other playlist. That playlist is displayed sorted as defined in the playlist definition which may or may not agree with the column headings.
Now click on the original playlist. It is displayed sorted as defined in the playlist definition which does not not agree with the column headings.

It would be good for the column heading to quit indicating that they are sorting when they are not.

Thanks,
-- Larry